Thermostat



Sept. 11, 1928. 1,683,908

P. S. MARTIN 4 THERMOSTAT Filed Nov. 1923 0 icff il/ I cubator'.

" Patented- Sept. 11. 1928.

PERRY S. EARTIN, OF HABBISONBUBG,

THEBMOSTAT.

Application filed November 2, 1m. Serial no. 672,444.

This invention relates to thermostats and has for its object the provision of an allmetal thermostat which will be more compact and also more powerful for a given 6 weight of metal than thermostats at present known.

A further object of the present invention is to provide a simple and efiicient. thermostat particular-l adapted for use in an ininvention are pointed out in the specification and are particularly set forth in the'claims following and relate generally to the specific forms-of the elements and the shielding of the retaining elements by the elements of greater expansion.

- Thermostats of the present day are genthermostatexpands it must not only overerally of the elongated bar type and expansion of -the metal in a single direction 20. only is utilized. This might seem to be the correct practice since the amount of expansion of a piece of metal is determined solely by its length and consequently pieces of metal held in thermostatic relationby rivets say five inches apart would expand-neither more or less than a similar bar of very different transverse shape if held by rivets spaced apart exactly the same distance.

Forthe ordinary run ot.work therefore but one dimension is useful but there are other conditionswhere it would seem advisable to take advantage if possible of the expension of both the length and breadth of the metal and this is particularly true with thermostats intended. for use in incubators and brooders where a considerable amount of power is required and in which the amount of'space availablefor the} thermostat is quite limited. 40 This taking advantage of the expansion of both the length and breadth of the metal is an area expansion and can lie just as well considered along: the lines of polar. coordinates' and described as radial and circumi ferential; That is; not only will thestress esaccumulate radially at the center-crossing and intersecting each other in all directions, but stresses' will accumulate along the edges of the. platesi-n a circumferential direction and these circumferential stresses will occur in-zones all the way from the. edges of the plates to their centers. All of these circumferential stresses ;will .cut" across all the radial stresses'thus sort of bracing .them and producing aiiiajchingor buckling that is well Still urther objects of the present a a An attachment means such as 23 is secured nigh irresistible so lon as the resistance to be overcome does not racture the metal.

The thermostats at present in use in-incubators are usually eighteen'inches or "more long and are consequently so large and clumsy that they have not been as widely used as the more compact fluid filled-wafers which are not well suited for this use owing to their many disadvantages. By making my thermostat of all metal and by utilizing .65 the expansion of both the length and breadth of the metal I have been able to. devise a thermostat which is small enough to be interchangeable in the regulator brackets w' the. small round wafer tioned. In incubator and brooder ,use when the come/the resistance of the elements but it must also move the damper or other mecha 76 nism to which it is attached in a rapid and positive manner. and this frequently requires, considerable power. In my device the amount of power is dependent solely upon- L the number ofunits used and I find in a 80 number of tests made in large hatcheries that excellent results may be obtained with from two to four elements only four inches square; this because'of the utilization of the crosswise andilengthwise expansion of the expanding members. v 7

In the drawings Figure 1 is a plan view of a' thermostatembodying the present invention.

Fig. 2 is an edge view thereof. I 4

Fig. 3 is a fragmentary section through the axis.

Fig. 4 is a view of a" thermostat element. having additiohal creases. 4

The sheets 10 and 11 are of steel or other strong and sturdy metal having a relatively low rate of expansion while the plates 15, 16, 17 and 18 are of a difl'erent metal and one having a relatively high rate of expansion. .In its simplest form the sheets 15 to 18 inclusive are each perfectly' flat and are secured in pairs on opposite sides of they supporting sheets 10, and. 11-; the adjacent members as 16 and 17 being secured together asby the rivet" 20 which is located in the axis of the elements whereas therivets 21- holding together the two expansive: sheets and the supporting sheet between them are located at the corners of the squares.

type just men- 7 0 I I I expansive element,'for examp e 178, is

at the .center, that is, at the axis of one at the outer expansive members} such as while it the other end of the ile the outer rovided in its center with a button 24v w ich presses against a movable portion of the mechanism to be operated by the thermostat. It will be' obvious that as many units as may be desired may be connected together in which case the boss 24 will be replaced by a rivet int-he same manner and for the same function as the rivet between the members 16 and 17. j In their preferred form the expensive plates 15, 16, etc.'are creased crosswise and iagonally as at .26 and 27 respectively so that the expansive sheets between rivets 'do 'not -lie flat against the supporting platesias 10.

The advantage of this construction is that.

the expansive force between adjacent. rivets is carried to the center or axis of the thermostat in-a more positive manner. I also find "it advantageous to eo'rruglate these sheets of While :the" drawings illustrate ,s uares is only, the idea can be carried out wit anyequilateral polygons such as triangles, entah go'ns, etc'., or with round plates, or wit any tially at 2. A' unit of a t ermostatic'pile comprisshape: whatsoever that" has substantial dimansions in all radial directions from the center. The .sheets preferably should not ,I

have radial sections cut out along.- the edges as this would diminish the accumulation of circumferential stresses.

the thermostat'shall actrapidlyand this advantage I secure because of the protection" very much quicker than the co 'parativelyf':

thick supporting sheets.

What I claim is: 1., An all-metal thermostat comprising,

three broad rectangular plates secured to-Q gether at theirfcorners the central plate'hav-.- ing a lower-coefiicient of expansion than the outside plates, the diagonals of the rectangles 4 crossing each other at the center suiistana right an le.

sheets to bow away from the supporting sheets through acen'tral axis.

.3. An all-metal thermostat comprising a plurality of units each'unit comprising a supporting sheets of relatively low expansion and a plurality of sheets mounted onopp'osite sides thereof of higher expansion, the sheets of higher expansion being creased out from the supporting sheet and radiating in more than two' direeti'ohs from thecenter.

4. An all-metal thermostat comprising a plurality of units each unit con1prisinga supporting sheet of relativelylow expansion and a lurality of sheets mounted on oppositesies thereof of higher expansion-,the sheets of hi her expansion being creased out from the su porting sheet in a longitudinal and a transverse direction. I

5, An all-metal thermostat comprising a plurality of units of substantial width each unit comprising a supporting sheet of rela tively low expansion and a plurality of sheets mounted on opposite sides thereof of higher expansion, the sheets of higher expansion being diagonally creased out from 1 the supporting sheet. a 4 v 6..An all metal thermostat'comprising a. plurality of equilateral polygon shaped units each unit: comprising a supporting sheet of relatively low expansion and a plurality of sheets mounted on opposite sides thereof of hi her expansion, the sheets of higher -expan-- slon being diagonally, transversely, and longitudinally creased out from the supporting sheet. In incubators it is quite important that 7. An all-metal thermostat comprising a plurality of units of substantial area in pro- 9. portion, to their greatest overall length each unit comprising a supporting shee of relatively low ex ansion' and a plurality of sheets mounte on opposite sides thereof of higher expansion, the sheets "of higher ex pansion'beingcorrugate'd radially out frome' lgportingsheet. a

" 8. all-metal thermostat comprising a plurality ofgunitseach unit comprising a supporting'sheet of relatively lowexpansion, anda plurality of'sheets'mounted on opposite sides thereof of higher expansiomi the sheets ofhigher expansionfbeing corrugated radially and. in addition being creased in lines assing through the center of the pilev at rig t angles to one another. I

. v PERRY S.- MARTIN. 

